调用java方法绘制图形

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calling a java method to draw graphics

我正在尝试在框架上绘制一些简单的图形。我还希望能够调整我从我的主要方法中绘制的内容。例如，设置要打印的字符串变量，或者矩形的坐标。

我似乎遇到的问题是在设置类变量之前调用了 paintComponent 方法。我将如何更改此代码以便能够在它绘制到屏幕之前设置 JPanel/JFrame 变量？

谢谢

import java.awt.*;

import javax.swing.*;



public class Test {



  public static void main(String[] args) {

    FrameTest test_frame = new FrameTest();

    test_frame.test_string ="I WANT TO DRAW THIS STRING";

  }

}



class FrameTest extends JFrame{

  private static final long serialVersionUID = 1L;

  String test_string;



  public FrameTest(){

    this.test_string ="TEMP STRING FROM FRAME";

    JFrame gui = new JFrame();

    gui.setTitle("Test Title");

    gui.setSize(400,400);

    gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



    Painting painting = new Painting();



    Container pane = gui.getContentPane();

    pane.setLayout(new GridLayout(1,1));



    pane.add(painting);

    gui.setVisible(true);



  }

}



class Painting extends JPanel{

  private static final long serialVersionUID = 1L;

  String test_string;



  public Painting(){

    setBackground(Color.WHITE);

    this.test_string ="TEMP STRING FROM PANEL";

  }



  public void paintComponent(Graphics g) {

    super.paintComponent(g);



    g.setColor(Color.RED);

    g.drawString(test_string, 20, 20);

  }

}

import java.awt.Color;

import java.awt.Container;

import java.awt.Graphics;

import java.awt.GridLayout;



import javax.swing.JFrame;

import javax.swing.JPanel;



public class Test {



  public static void main(String[] args) {

    FrameTest1 test_frame = new FrameTest1();

    test_frame.setContentString("I WANT TO DRAW THIS STRING");

  }



}



class FrameTest1 extends JFrame {

  private static final long serialVersionUID = 1L;



  Painting painting = new Painting();



  public FrameTest1() {

    JFrame gui = new JFrame();

    gui.setTitle("Test Title");

    gui.setSize(400, 400);

    gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



    Container pane = gui.getContentPane();

    pane.setLayout(new GridLayout(1, 1));



    pane.add(painting);

    gui.setVisible(true);



  }



  public void setContentString(String value) {

    painting.test_string = value;

  }

}



class Painting extends JPanel {

  private static final long serialVersionUID = 1L;

  String test_string;



  public Painting() {

    setBackground(Color.WHITE);

    this.test_string ="TEMP STRING FROM PANEL";

  }



  public void paintComponent(Graphics g) {

    super.paintComponent(g);



    g.setColor(Color.RED);

    g.drawString(test_string, 20, 20);

  }

}
test_frame.test_string ="I WANT TO DRAW THIS STRING";

public void setTestString(String test_string) {

  painting.setTestString(test_string);

}
FrameTest test_frame = new FrameTest();

test_frame.setTestString("I WANT TO DRAW THIS STRING");

import java.awt.*;

import java.awt.event.*;

import java.awt.image.BufferedImage;

import javax.swing.*;

import javax.swing.border.EmptyBorder;

import java.util.Random;



public class ImageViewer {

  

  JPanel gui;

  /** Displays the image. */

  JLabel imageCanvas;



  /** Set the image as icon of the image canvas (display it). */

  public void setImage(Image image) {

    imageCanvas.setIcon(new ImageIcon(image));

  }

  

  public void initComponents() {

    if (gui==null) { 

      gui = new JPanel(new BorderLayout());

      gui.setBorder(new EmptyBorder(5,5,5,5));

      imageCanvas = new JLabel();

      

      JPanel imageCenter = new JPanel(new GridBagLayout());

      imageCenter.add(imageCanvas);

      JScrollPane imageScroll = new JScrollPane(imageCenter);

      imageScroll.setPreferredSize(new Dimension(300,100));

      gui.add(imageScroll, BorderLayout.CENTER);

    }

  }

  

  public Container getGui() {

    initComponents();

    return gui;

  }

  

  public static Image getRandomImage(Random random) {

    int w = 100 + random.nextInt(400);

    int h = 50 + random.nextInt(200);

    BufferedImage bi = new BufferedImage(

        w,h,BufferedImage.TYPE_INT_RGB);

    

    return bi;

  }



  public static void main(String[] args) throws Exception {

    Runnable r = new Runnable() {

      @Override

      public void run() {

        JFrame f = new JFrame("Image Viewer");

        // TODO Fix kludge to kill the Timer

        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

      

        final ImageViewer viewer = new ImageViewer();

        f.setContentPane(viewer.getGui());

        

        f.pack();

        f.setLocationByPlatform(true);

        f.setVisible(true);



        ActionListener animate = new ActionListener() {



          Random random = new Random();

          

          @Override

          public void actionPerformed(ActionEvent arg0) {

            viewer.setImage(getRandomImage(random));

          }

        };

        Timer timer = new Timer(1500,animate);

        timer.start();

      }

    };

    SwingUtilities.invokeLater(r);

  }

}

import java.awt.*;

import javax.swing.*;



public class Test {



  public static void main(String[] args) {

    Painting painting = new Painting("I WANT TO DRAW THIS STRING");

    FrameTest test_frame = new FrameTest(painting);

  }

}



class FrameTest extends JFrame{

  private static final long serialVersionUID = 1L;

  String test_string;



  public FrameTest(painting){

    super();

    this.test_string ="TEMP STRING FROM FRAME";

    JFrame gui = new JFrame();

    gui.setTitle("Test Title");

    gui.setSize(400,400);

    gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



    Container pane = gui.getContentPane();

    pane.setLayout(new GridLayout(1,1));



    pane.add(painting);

    gui.setVisible(true);



  }

}



class Painting extends JPanel{

  private static final long serialVersionUID = 1L;

  String test_string;



  public Painting(String test_string){

    super();

    this.test_string = test_string;

    setBackground(Color.WHITE);

  }



  public void paintComponent(Graphics g) {

    super.paintComponent(g);



    g.setColor(Color.RED);

    g.drawString(test_string, 20, 20);

  }

}

从 FrameTest 类中删除 test_string。直接使用 set 方法设置 test_string。参见示例：

import java.awt.*;

import javax.swing.*;



public class Test {



  public static void main(String[] args) {

    FrameTest test_frame = new FrameTest();

    test_frame.test_string ="I WANT TO DRAW THIS STRING";

  }

}



class FrameTest extends JFrame{

  private static final long serialVersionUID = 1L;

  String test_string;



  public FrameTest(){

    this.test_string ="TEMP STRING FROM FRAME";

    JFrame gui = new JFrame();

    gui.setTitle("Test Title");

    gui.setSize(400,400);

    gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



    Painting painting = new Painting();



    Container pane = gui.getContentPane();

    pane.setLayout(new GridLayout(1,1));



    pane.add(painting);

    gui.setVisible(true);



  }

}



class Painting extends JPanel{

  private static final long serialVersionUID = 1L;

  String test_string;



  public Painting(){

    setBackground(Color.WHITE);

    this.test_string ="TEMP STRING FROM PANEL";

  }



  public void paintComponent(Graphics g) {

    super.paintComponent(g);



    g.setColor(Color.RED);

    g.drawString(test_string, 20, 20);

  }

}

import java.awt.Color;

import java.awt.Container;

import java.awt.Graphics;

import java.awt.GridLayout;



import javax.swing.JFrame;

import javax.swing.JPanel;



public class Test {



  public static void main(String[] args) {

    FrameTest1 test_frame = new FrameTest1();

    test_frame.setContentString("I WANT TO DRAW THIS STRING");

  }



}



class FrameTest1 extends JFrame {

  private static final long serialVersionUID = 1L;



  Painting painting = new Painting();



  public FrameTest1() {

    JFrame gui = new JFrame();

    gui.setTitle("Test Title");

    gui.setSize(400, 400);

    gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



    Container pane = gui.getContentPane();

    pane.setLayout(new GridLayout(1, 1));



    pane.add(painting);

    gui.setVisible(true);



  }



  public void setContentString(String value) {

    painting.test_string = value;

  }

}



class Painting extends JPanel {

  private static final long serialVersionUID = 1L;

  String test_string;



  public Painting() {

    setBackground(Color.WHITE);

    this.test_string ="TEMP STRING FROM PANEL";

  }



  public void paintComponent(Graphics g) {

    super.paintComponent(g);



    g.setColor(Color.RED);

    g.drawString(test_string, 20, 20);

  }

}
test_frame.test_string ="I WANT TO DRAW THIS STRING";

public void setTestString(String test_string) {

  painting.setTestString(test_string);

}
FrameTest test_frame = new FrameTest();

test_frame.setTestString("I WANT TO DRAW THIS STRING");

import java.awt.*;

import java.awt.event.*;

import java.awt.image.BufferedImage;

import javax.swing.*;

import javax.swing.border.EmptyBorder;

import java.util.Random;



public class ImageViewer {

  

  JPanel gui;

  /** Displays the image. */

  JLabel imageCanvas;



  /** Set the image as icon of the image canvas (display it). */

  public void setImage(Image image) {

    imageCanvas.setIcon(new ImageIcon(image));

  }

  

  public void initComponents() {

    if (gui==null) { 

      gui = new JPanel(new BorderLayout());

      gui.setBorder(new EmptyBorder(5,5,5,5));

      imageCanvas = new JLabel();

      

      JPanel imageCenter = new JPanel(new GridBagLayout());

      imageCenter.add(imageCanvas);

      JScrollPane imageScroll = new JScrollPane(imageCenter);

      imageScroll.setPreferredSize(new Dimension(300,100));

      gui.add(imageScroll, BorderLayout.CENTER);

    }

  }

  

  public Container getGui() {

    initComponents();

    return gui;

  }

  

  public static Image getRandomImage(Random random) {

    int w = 100 + random.nextInt(400);

    int h = 50 + random.nextInt(200);

    BufferedImage bi = new BufferedImage(

        w,h,BufferedImage.TYPE_INT_RGB);

    

    return bi;

  }



  public static void main(String[] args) throws Exception {

    Runnable r = new Runnable() {

      @Override

      public void run() {

        JFrame f = new JFrame("Image Viewer");

        // TODO Fix kludge to kill the Timer

        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

      

        final ImageViewer viewer = new ImageViewer();

        f.setContentPane(viewer.getGui());

        

        f.pack();

        f.setLocationByPlatform(true);

        f.setVisible(true);



        ActionListener animate = new ActionListener() {



          Random random = new Random();

          

          @Override

          public void actionPerformed(ActionEvent arg0) {

            viewer.setImage(getRandomImage(random));

          }

        };

        Timer timer = new Timer(1500,animate);

        timer.start();

      }

    };

    SwingUtilities.invokeLater(r);

  }

}

import java.awt.*;

import javax.swing.*;



public class Test {



  public static void main(String[] args) {

    Painting painting = new Painting("I WANT TO DRAW THIS STRING");

    FrameTest test_frame = new FrameTest(painting);

  }

}



class FrameTest extends JFrame{

  private static final long serialVersionUID = 1L;

  String test_string;



  public FrameTest(painting){

    super();

    this.test_string ="TEMP STRING FROM FRAME";

    JFrame gui = new JFrame();

    gui.setTitle("Test Title");

    gui.setSize(400,400);

    gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



    Container pane = gui.getContentPane();

    pane.setLayout(new GridLayout(1,1));



    pane.add(painting);

    gui.setVisible(true);



  }

}



class Painting extends JPanel{

  private static final long serialVersionUID = 1L;

  String test_string;



  public Painting(String test_string){

    super();

    this.test_string = test_string;

    setBackground(Color.WHITE);

  }



  public void paintComponent(Graphics g) {

    super.paintComponent(g);



    g.setColor(Color.RED);

    g.drawString(test_string, 20, 20);

  }

}

在这里，您将一个字符串分配给 FrameTest 中的 test_string，它不会更新 Painting:

中的同名变量

import java.awt.*;

import javax.swing.*;



public class Test {



  public static void main(String[] args) {

    FrameTest test_frame = new FrameTest();

    test_frame.test_string ="I WANT TO DRAW THIS STRING";

  }

}



class FrameTest extends JFrame{

  private static final long serialVersionUID = 1L;

  String test_string;



  public FrameTest(){

    this.test_string ="TEMP STRING FROM FRAME";

    JFrame gui = new JFrame();

    gui.setTitle("Test Title");

    gui.setSize(400,400);

    gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



    Painting painting = new Painting();



    Container pane = gui.getContentPane();

    pane.setLayout(new GridLayout(1,1));



    pane.add(painting);

    gui.setVisible(true);



  }

}



class Painting extends JPanel{

  private static final long serialVersionUID = 1L;

  String test_string;



  public Painting(){

    setBackground(Color.WHITE);

    this.test_string ="TEMP STRING FROM PANEL";

  }



  public void paintComponent(Graphics g) {

    super.paintComponent(g);



    g.setColor(Color.RED);

    g.drawString(test_string, 20, 20);

  }

}

import java.awt.Color;

import java.awt.Container;

import java.awt.Graphics;

import java.awt.GridLayout;



import javax.swing.JFrame;

import javax.swing.JPanel;



public class Test {



  public static void main(String[] args) {

    FrameTest1 test_frame = new FrameTest1();

    test_frame.setContentString("I WANT TO DRAW THIS STRING");

  }



}



class FrameTest1 extends JFrame {

  private static final long serialVersionUID = 1L;



  Painting painting = new Painting();



  public FrameTest1() {

    JFrame gui = new JFrame();

    gui.setTitle("Test Title");

    gui.setSize(400, 400);

    gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



    Container pane = gui.getContentPane();

    pane.setLayout(new GridLayout(1, 1));



    pane.add(painting);

    gui.setVisible(true);



  }



  public void setContentString(String value) {

    painting.test_string = value;

  }

}



class Painting extends JPanel {

  private static final long serialVersionUID = 1L;

  String test_string;



  public Painting() {

    setBackground(Color.WHITE);

    this.test_string ="TEMP STRING FROM PANEL";

  }



  public void paintComponent(Graphics g) {

    super.paintComponent(g);



    g.setColor(Color.RED);

    g.drawString(test_string, 20, 20);

  }

}
test_frame.test_string ="I WANT TO DRAW THIS STRING";

public void setTestString(String test_string) {

  painting.setTestString(test_string);

}
FrameTest test_frame = new FrameTest();

test_frame.setTestString("I WANT TO DRAW THIS STRING");

import java.awt.*;

import java.awt.event.*;

import java.awt.image.BufferedImage;

import javax.swing.*;

import javax.swing.border.EmptyBorder;

import java.util.Random;



public class ImageViewer {

  

  JPanel gui;

  /** Displays the image. */

  JLabel imageCanvas;



  /** Set the image as icon of the image canvas (display it). */

  public void setImage(Image image) {

    imageCanvas.setIcon(new ImageIcon(image));

  }

  

  public void initComponents() {

    if (gui==null) { 

      gui = new JPanel(new BorderLayout());

      gui.setBorder(new EmptyBorder(5,5,5,5));

      imageCanvas = new JLabel();

      

      JPanel imageCenter = new JPanel(new GridBagLayout());

      imageCenter.add(imageCanvas);

      JScrollPane imageScroll = new JScrollPane(imageCenter);

      imageScroll.setPreferredSize(new Dimension(300,100));

      gui.add(imageScroll, BorderLayout.CENTER);

    }

  }

  

  public Container getGui() {

    initComponents();

    return gui;

  }

  

  public static Image getRandomImage(Random random) {

    int w = 100 + random.nextInt(400);

    int h = 50 + random.nextInt(200);

    BufferedImage bi = new BufferedImage(

        w,h,BufferedImage.TYPE_INT_RGB);

    

    return bi;

  }



  public static void main(String[] args) throws Exception {

    Runnable r = new Runnable() {

      @Override

      public void run() {

        JFrame f = new JFrame("Image Viewer");

        // TODO Fix kludge to kill the Timer

        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

      

        final ImageViewer viewer = new ImageViewer();

        f.setContentPane(viewer.getGui());

        

        f.pack();

        f.setLocationByPlatform(true);

        f.setVisible(true);



        ActionListener animate = new ActionListener() {



          Random random = new Random();

          

          @Override

          public void actionPerformed(ActionEvent arg0) {

            viewer.setImage(getRandomImage(random));

          }

        };

        Timer timer = new Timer(1500,animate);

        timer.start();

      }

    };

    SwingUtilities.invokeLater(r);

  }

}

import java.awt.*;

import javax.swing.*;



public class Test {



  public static void main(String[] args) {

    Painting painting = new Painting("I WANT TO DRAW THIS STRING");

    FrameTest test_frame = new FrameTest(painting);

  }

}



class FrameTest extends JFrame{

  private static final long serialVersionUID = 1L;

  String test_string;



  public FrameTest(painting){

    super();

    this.test_string ="TEMP STRING FROM FRAME";

    JFrame gui = new JFrame();

    gui.setTitle("Test Title");

    gui.setSize(400,400);

    gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



    Container pane = gui.getContentPane();

    pane.setLayout(new GridLayout(1,1));



    pane.add(painting);

    gui.setVisible(true);



  }

}



class Painting extends JPanel{

  private static final long serialVersionUID = 1L;

  String test_string;



  public Painting(String test_string){

    super();

    this.test_string = test_string;

    setBackground(Color.WHITE);

  }



  public void paintComponent(Graphics g) {

    super.paintComponent(g);



    g.setColor(Color.RED);

    g.drawString(test_string, 20, 20);

  }

}

为什么不向 FrameTest 添加一个更新方法，因为您对此有参考：

import java.awt.*;

import javax.swing.*;



public class Test {



  public static void main(String[] args) {

    FrameTest test_frame = new FrameTest();

    test_frame.test_string ="I WANT TO DRAW THIS STRING";

  }

}



class FrameTest extends JFrame{

  private static final long serialVersionUID = 1L;

  String test_string;



  public FrameTest(){

    this.test_string ="TEMP STRING FROM FRAME";

    JFrame gui = new JFrame();

    gui.setTitle("Test Title");

    gui.setSize(400,400);

    gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



    Painting painting = new Painting();



    Container pane = gui.getContentPane();

    pane.setLayout(new GridLayout(1,1));



    pane.add(painting);

    gui.setVisible(true);



  }

}



class Painting extends JPanel{

  private static final long serialVersionUID = 1L;

  String test_string;



  public Painting(){

    setBackground(Color.WHITE);

    this.test_string ="TEMP STRING FROM PANEL";

  }



  public void paintComponent(Graphics g) {

    super.paintComponent(g);



    g.setColor(Color.RED);

    g.drawString(test_string, 20, 20);

  }

}

import java.awt.Color;

import java.awt.Container;

import java.awt.Graphics;

import java.awt.GridLayout;



import javax.swing.JFrame;

import javax.swing.JPanel;



public class Test {



  public static void main(String[] args) {

    FrameTest1 test_frame = new FrameTest1();

    test_frame.setContentString("I WANT TO DRAW THIS STRING");

  }



}



class FrameTest1 extends JFrame {

  private static final long serialVersionUID = 1L;



  Painting painting = new Painting();



  public FrameTest1() {

    JFrame gui = new JFrame();

    gui.setTitle("Test Title");

    gui.setSize(400, 400);

    gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



    Container pane = gui.getContentPane();

    pane.setLayout(new GridLayout(1, 1));



    pane.add(painting);

    gui.setVisible(true);



  }



  public void setContentString(String value) {

    painting.test_string = value;

  }

}



class Painting extends JPanel {

  private static final long serialVersionUID = 1L;

  String test_string;



  public Painting() {

    setBackground(Color.WHITE);

    this.test_string ="TEMP STRING FROM PANEL";

  }



  public void paintComponent(Graphics g) {

    super.paintComponent(g);



    g.setColor(Color.RED);

    g.drawString(test_string, 20, 20);

  }

}
test_frame.test_string ="I WANT TO DRAW THIS STRING";

public void setTestString(String test_string) {

  painting.setTestString(test_string);

}
FrameTest test_frame = new FrameTest();

test_frame.setTestString("I WANT TO DRAW THIS STRING");

import java.awt.*;

import java.awt.event.*;

import java.awt.image.BufferedImage;

import javax.swing.*;

import javax.swing.border.EmptyBorder;

import java.util.Random;



public class ImageViewer {

  

  JPanel gui;

  /** Displays the image. */

  JLabel imageCanvas;



  /** Set the image as icon of the image canvas (display it). */

  public void setImage(Image image) {

    imageCanvas.setIcon(new ImageIcon(image));

  }

  

  public void initComponents() {

    if (gui==null) { 

      gui = new JPanel(new BorderLayout());

      gui.setBorder(new EmptyBorder(5,5,5,5));

      imageCanvas = new JLabel();

      

      JPanel imageCenter = new JPanel(new GridBagLayout());

      imageCenter.add(imageCanvas);

      JScrollPane imageScroll = new JScrollPane(imageCenter);

      imageScroll.setPreferredSize(new Dimension(300,100));

      gui.add(imageScroll, BorderLayout.CENTER);

    }

  }

  

  public Container getGui() {

    initComponents();

    return gui;

  }

  

  public static Image getRandomImage(Random random) {

    int w = 100 + random.nextInt(400);

    int h = 50 + random.nextInt(200);

    BufferedImage bi = new BufferedImage(

        w,h,BufferedImage.TYPE_INT_RGB);

    

    return bi;

  }



  public static void main(String[] args) throws Exception {

    Runnable r = new Runnable() {

      @Override

      public void run() {

        JFrame f = new JFrame("Image Viewer");

        // TODO Fix kludge to kill the Timer

        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

      

        final ImageViewer viewer = new ImageViewer();

        f.setContentPane(viewer.getGui());

        

        f.pack();

        f.setLocationByPlatform(true);

        f.setVisible(true);



        ActionListener animate = new ActionListener() {



          Random random = new Random();

          

          @Override

          public void actionPerformed(ActionEvent arg0) {

            viewer.setImage(getRandomImage(random));

          }

        };

        Timer timer = new Timer(1500,animate);

        timer.start();

      }

    };

    SwingUtilities.invokeLater(r);

  }

}

import java.awt.*;

import javax.swing.*;



public class Test {



  public static void main(String[] args) {

    Painting painting = new Painting("I WANT TO DRAW THIS STRING");

    FrameTest test_frame = new FrameTest(painting);

  }

}



class FrameTest extends JFrame{

  private static final long serialVersionUID = 1L;

  String test_string;



  public FrameTest(painting){

    super();

    this.test_string ="TEMP STRING FROM FRAME";

    JFrame gui = new JFrame();

    gui.setTitle("Test Title");

    gui.setSize(400,400);

    gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



    Container pane = gui.getContentPane();

    pane.setLayout(new GridLayout(1,1));



    pane.add(painting);

    gui.setVisible(true);



  }

}



class Painting extends JPanel{

  private static final long serialVersionUID = 1L;

  String test_string;



  public Painting(String test_string){

    super();

    this.test_string = test_string;

    setBackground(Color.WHITE);

  }



  public void paintComponent(Graphics g) {

    super.paintComponent(g);



    g.setColor(Color.RED);

    g.drawString(test_string, 20, 20);

  }

}

并调用：

import java.awt.*;

import javax.swing.*;



public class Test {



  public static void main(String[] args) {

    FrameTest test_frame = new FrameTest();

    test_frame.test_string ="I WANT TO DRAW THIS STRING";

  }

}



class FrameTest extends JFrame{

  private static final long serialVersionUID = 1L;

  String test_string;



  public FrameTest(){

    this.test_string ="TEMP STRING FROM FRAME";

    JFrame gui = new JFrame();

    gui.setTitle("Test Title");

    gui.setSize(400,400);

    gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



    Painting painting = new Painting();



    Container pane = gui.getContentPane();

    pane.setLayout(new GridLayout(1,1));



    pane.add(painting);

    gui.setVisible(true);



  }

}



class Painting extends JPanel{

  private static final long serialVersionUID = 1L;

  String test_string;



  public Painting(){

    setBackground(Color.WHITE);

    this.test_string ="TEMP STRING FROM PANEL";

  }



  public void paintComponent(Graphics g) {

    super.paintComponent(g);



    g.setColor(Color.RED);

    g.drawString(test_string, 20, 20);

  }

}

import java.awt.Color;

import java.awt.Container;

import java.awt.Graphics;

import java.awt.GridLayout;



import javax.swing.JFrame;

import javax.swing.JPanel;



public class Test {



  public static void main(String[] args) {

    FrameTest1 test_frame = new FrameTest1();

    test_frame.setContentString("I WANT TO DRAW THIS STRING");

  }



}



class FrameTest1 extends JFrame {

  private static final long serialVersionUID = 1L;



  Painting painting = new Painting();



  public FrameTest1() {

    JFrame gui = new JFrame();

    gui.setTitle("Test Title");

    gui.setSize(400, 400);

    gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



    Container pane = gui.getContentPane();

    pane.setLayout(new GridLayout(1, 1));



    pane.add(painting);

    gui.setVisible(true);



  }



  public void setContentString(String value) {

    painting.test_string = value;

  }

}



class Painting extends JPanel {

  private static final long serialVersionUID = 1L;

  String test_string;



  public Painting() {

    setBackground(Color.WHITE);

    this.test_string ="TEMP STRING FROM PANEL";

  }



  public void paintComponent(Graphics g) {

    super.paintComponent(g);



    g.setColor(Color.RED);

    g.drawString(test_string, 20, 20);

  }

}
test_frame.test_string ="I WANT TO DRAW THIS STRING";

public void setTestString(String test_string) {

  painting.setTestString(test_string);

}
FrameTest test_frame = new FrameTest();

test_frame.setTestString("I WANT TO DRAW THIS STRING");

import java.awt.*;

import java.awt.event.*;

import java.awt.image.BufferedImage;

import javax.swing.*;

import javax.swing.border.EmptyBorder;

import java.util.Random;



public class ImageViewer {

  

  JPanel gui;

  /** Displays the image. */

  JLabel imageCanvas;



  /** Set the image as icon of the image canvas (display it). */

  public void setImage(Image image) {

    imageCanvas.setIcon(new ImageIcon(image));

  }

  

  public void initComponents() {

    if (gui==null) { 

      gui = new JPanel(new BorderLayout());

      gui.setBorder(new EmptyBorder(5,5,5,5));

      imageCanvas = new 
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