java - 在 Applet 中调用函数 repaint() 后如何重新绘制？

Question

我知道 repaint() 函数不会立即重新绘制框架。但是，这里的 repaint 方法是在递归函数期间调用的，并且仅在 towerOfHanoi 函数完成后才重新绘制。是否有在递归函数迭代期间每次立即调用绘制函数进行重新绘制的方法？

public void actionPerformed(ActionEvent e) {
    if (e.getSource() == start) {
        num = number.getText().trim();  
        numDisks = Integer.parseInt(num);

        //start the tower of hanoi function catch block used because of the delay function
        repaint();

        height[0].changeHeight(numDisks);
        begin = true;
        towerOfHanoi(numDisks, 0, 2, 1);
        //repaint();
    }

}


//initialize the pegs; first thing called when applet starts
public void paint(Graphics g) {
    g.setColor(Color.BLUE);
    g.fillRect(20, 190, 560, 10); //base
    g.fillRect(70, 60, 10, 150); //first peg
    g.fillRect(300, 60, 10, 150); //second peg
    g.fillRect(530, 60, 10, 150); //third peg

    //create the painting based on the amount of disks, starting with the biggest disk. 
    //when this is repainted, it will draw the new disks in different pegs with different coordinates
    g.setColor(Color.RED);
    for (int i = 0; i < numDisks; i++) {
        g.fillRect(disks[i].xPos, disks[i].yPos, disks[i].width, 10);
    }
}

public void update(Graphics g) {
    paint(g);
}


public void towerOfHanoi(int N, int from, int to, int temp) {

    if (N == 1) {
        moveTo(from, to, N);
    }
    else {
        towerOfHanoi(N - 1, from, temp, to);
        moveTo(from, to, N);
        towerOfHanoi(N - 1, temp, to, from);
    }
}

//change move to function move disks from 1st stack to the 3rd stack
public void moveTo(int from, int to, int diskNum)  {        
    System.out.println(from + "->" + to);

    //adjust the disk number to match the indexing of the way I 
    //used the disk number, as an index of arrays starting from
    //the bottom up at 0.
    if (numDisks == 1) {
        if (diskNum == 1) { diskNum = 0;}
    }
    else if (numDisks == 2) {
        if (diskNum == 1) {diskNum = 1; }
        else if (diskNum == 2) {diskNum = 0; }
    }
    else if (numDisks == 3) {
        if (diskNum == 1) { diskNum = 2;}
        else if (diskNum == 2) {diskNum = 1;}
        else if (diskNum == 3) {diskNum = 0;}
    }
    else if (numDisks == 4) {
        if (diskNum == 1) { diskNum = 3;}
        else if (diskNum == 2) {diskNum = 2;}
        else if (diskNum == 3) {diskNum = 1;}
        else if (diskNum == 4) {diskNum = 0;}
    }
    else if (numDisks == 5) {
        if (diskNum == 1) { diskNum = 4;}
        else if (diskNum == 2) {diskNum = 3;}
        else if (diskNum == 3) {diskNum = 2;}
        else if (diskNum == 4) {diskNum = 1;}
        else if (diskNum == 5) {diskNum = 0;}
    }
    else if (numDisks == 6) {
        if (diskNum == 1) { diskNum = 5;}
        else if (diskNum == 2) {diskNum = 4;}
        else if (diskNum == 3) {diskNum = 3;}
        else if (diskNum == 4) {diskNum = 2;}
        else if (diskNum == 5) {diskNum = 1;}
        else if (diskNum == 6) {diskNum = 0;}
    }
    else if (numDisks == 7) {
        if (diskNum == 1) { diskNum = 6;}
        else if (diskNum == 2) {diskNum = 5;}
        else if (diskNum == 3) {diskNum = 4;}
        else if (diskNum == 4) {diskNum = 3;}
        else if (diskNum == 5) {diskNum = 2;}
        else if (diskNum == 6) {diskNum = 1;}
        else if (diskNum == 7) {diskNum = 0;}
    }   


    //diskNum += height[from].height;
    System.out.println("Disk moving is disk # " + diskNum);
    topDisk = diskNum;

    height[from].pop();
    height[to].push();

    System.out.println("Height of Peg 1: " + height[0].height);
    System.out.println("Height of Peg 2: " + height[1].height);
    System.out.println("Height of Peg 3: " + height[2].height);
    /* we can do this the hard way and calculate the xPos and yPos
     * We might just have to create the disk1 - disk7 each with its own widths, every disk 
     * has the same height. Every disk has its own xPos and yPos.
     * when we do that, we will then need to calculate the appropriate xPos for each..
     * but how do we calculate the yPos????? 
     * yPos is calculated based on the height of the pegs...
     * So now how do we calculate what the top disk number is?
     *  
    */  


    if (from == 0 && to == 1) { //adjust the new xPos
        disks[topDisk].from0to1(); //change xPos
        if (height[1].height == 0) { //adjusts the new yPos
            disks[topDisk].yPos = 175;
        } else if (height[1].height == 1) {
            disks[topDisk].yPos = 165;
        } else if (height[1].height == 2) {
            disks[topDisk].yPos = 155;
        } else if (height[1].height == 3) {
            disks[topDisk].yPos = 145;
        } else if (height[1].height == 4) {
            disks[topDisk].yPos = 135;
        } else if (height[1].height == 5) {
            disks[topDisk].yPos = 125;
        } else if (height[1].height == 6) {
            disks[topDisk].yPos = 115;
        } else if (height[1].height == 7) {
            disks[topDisk].yPos = 105;
        }
    } else if (from == 1 && to == 2) {
        disks[topDisk].from1to2();
        if (height[2].height == 0) { //adjusts the new yPos
            disks[topDisk].yPos = 175;
        } else if (height[2].height == 1) {
            disks[topDisk].yPos = 165;
        } else if (height[2].height == 2) {
            disks[topDisk].yPos = 155;
        } else if (height[2].height == 3) {
            disks[topDisk].yPos = 145;
        } else if (height[2].height == 4) {
            disks[topDisk].yPos = 135;
        } else if (height[2].height == 5) {
            disks[topDisk].yPos = 125;
        } else if (height[2].height == 6) {
            disks[topDisk].yPos = 115;
        } else if (height[2].height == 7) {
            disks[topDisk].yPos = 105;
        }
    } else if (from == 0 && to == 2) {
        disks[topDisk].from0to2();
        if (height[2].height == 0) { //adjusts the new yPos
            disks[topDisk].yPos = 175;
        } else if (height[2].height == 1) {
            disks[topDisk].yPos = 165;
        } else if (height[2].height == 2) {
            disks[topDisk].yPos = 155;
        } else if (height[2].height == 3) {
            disks[topDisk].yPos = 145;
        } else if (height[2].height == 4) {
            disks[topDisk].yPos = 135;
        } else if (height[2].height == 5) {
            disks[topDisk].yPos = 125;
        } else if (height[2].height == 6) {
            disks[topDisk].yPos = 115;
        } else if (height[2].height == 7) {
            disks[topDisk].yPos = 105;
        }
    } else if (from == 1 && to == 0) {
        disks[topDisk].from1to0();
        if (height[0].height == 0) { //adjusts the new yPos
            disks[topDisk].yPos = 175;
        } else if (height[0].height == 1) {
            disks[topDisk].yPos = 165;
        } else if (height[0].height == 2) {
            disks[topDisk].yPos = 155;
        } else if (height[0].height == 3) {
            disks[topDisk].yPos = 145;
        } else if (height[0].height == 4) {
            disks[topDisk].yPos = 135;
        } else if (height[0].height == 5) {
            disks[topDisk].yPos = 125;
        } else if (height[0].height == 6) {
            disks[topDisk].yPos = 115;
        } else if (height[0].height == 7) {
            disks[topDisk].yPos = 105;
        }
    } else if (from == 2 && to == 0) {
        disks[topDisk].from2to0();
        if (height[0].height == 0) { //adjusts the new yPos
            disks[topDisk].yPos = 175;
        } else if (height[0].height == 1) {
            disks[topDisk].yPos = 165;
        } else if (height[0].height == 2) {
            disks[topDisk].yPos = 155;
        } else if (height[0].height == 3) {
            disks[topDisk].yPos = 145;
        } else if (height[0].height == 4) {
            disks[topDisk].yPos = 135;
        } else if (height[0].height == 5) {
            disks[topDisk].yPos = 125;
        } else if (height[0].height == 6) {
            disks[topDisk].yPos = 115;
        } else if (height[0].height == 7) {
            disks[topDisk].yPos = 105;
        }
    } else if (from == 2 && to == 1) {
        disks[topDisk].from2to1();
        if (height[1].height == 0) { //adjusts the new yPos
            disks[topDisk].yPos = 175;
        } else if (height[1].height == 1) {
            disks[topDisk].yPos = 165;
        } else if (height[1].height == 2) {
            disks[topDisk].yPos = 155;
        } else if (height[1].height == 3) {
            disks[topDisk].yPos = 145;
        } else if (height[1].height == 4) {
            disks[topDisk].yPos = 135;
        } else if (height[1].height == 5) {
            disks[topDisk].yPos = 125;
        } else if (height[1].height == 6) {
            disks[topDisk].yPos = 115;
        } else if (height[1].height == 7) {
            disks[topDisk].yPos = 105;
        }
    }
    try {
        Thread.sleep(50);
    } catch(Exception ex) {

    }
    repaint();
}

Answer 1

一旦 UI 线程可用，

repaint() 就会发送一条重新绘制屏幕的指令。如果您还没有这样做，我建议您在不同的线程中完成所有转换，然后 repaint() 将相对较快地刷新屏幕(因为 UI 线程不执行任何操作)。