求教大神：关于触摸屏事件的异常处理

[SAKA007]

设计图形绘制类TestView(自定义组件)
package com.example.lenovo.ex4_3;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

class TestView extends View {
int x = 150, y = 50;

public TestView(Context context, AttributeSet attrs)
{
super(context, attrs);
}

void getXY(int _x, int _y) {
x = _x;
y = _y;
}

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawColor(Color.CYAN);
Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setColor(Color.BLUE);
canvas.drawCircle(x, y, 30, paint);
paint.setColor(Color.WHITE);
canvas.drawCircle(x - 9, y - 9, 6, paint);
}
}
把自定义组件添加到布局文件中：
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"

tools:context="com.example.lenovo.ex4_3.MainActivity">
<com.example.lenovo.ex4_3.TestView
android:id="@+id/testview1"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
/>
</RelativeLayout>
设计主控制文件MainActivity.java:
package com.example.lenovo.ex4_3;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.graphics.drawable.Drawable;
public class MainActivity extends AppCompatActivity {
TestView tView=null ;
@Override

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
tView = (TestView) findViewById(R.id.testview1);

if(tView == null){
Log.d("测试textView3==null","textView3==null");
}
else{
tView.setOnTouchListener(new mOnTouch());
}

setContentView(R.layout.activity_main);

}
public interface OnTouchListener{

}
class mOnTouch implements View.OnTouchListener{

public boolean onTouch(View v, MotionEvent event) {
int x1, y1;
x1 = (int) event.getX();
y1 = (int) event.getY();
if (event.getAction() == MotionEvent.ACTION_POINTER_DOWN)
{
tView.getXY(x1,y1);
tView.invalidate();
return true;
}
else if (event.getAction() == MotionEvent.ACTION_HOVER_MOVE) {
tView.getXY(x1, y1);
tView.invalidate();
return true;
}
return tView.onTouchEvent(event);
}
}
}
之前报的空指针错误，稍微改了下但是还是没有点击实现触摸效果，求教！！

[键盘舞者113]

改好了

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;

public class TestView extends View {
    int x = 150, y = 50;

    public TestView(Context context, AttributeSet attrs)
    {
        super(context, attrs);
    }

    void getXY(int _x, int _y) {
        x = _x;
        y = _y;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawColor(Color.CYAN);
        Paint paint = new Paint();
        paint.setAntiAlias(true);
        paint.setColor(Color.BLUE);
        canvas.drawCircle(x, y, 30, paint);
        paint.setColor(Color.WHITE);
        canvas.drawCircle(x - 9, y - 9, 6, paint);
    }



    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        int x1, y1;

        if (event.getAction() == MotionEvent.ACTION_DOWN)
        {
            x1 = (int) event.getX();
            y1 = (int) event.getY();
            getXY(x1,y1);
            invalidate();
            return true;
        }
        else if (event.getAction() == MotionEvent.ACTION_MOVE) {
            x1 = (int) event.getX();
            y1 = (int) event.getY();
            getXY(x1, y1);
            invalidate();
            return true;
        }
        return super.dispatchTouchEvent(event);
    }
}

public class MainActivity extends AppCompatActivity {
    TestView tView=null ;
    @Override

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_two);
        tView = (TestView) findViewById(R.id.testview1);
    }

}

[SAKA007]

真的非常感谢您！我是新手，能多请教您一个问题吗，为什么我之前用的tView.setOnTouchListener(new mOnTouch()) 设置监听事件就不行呢？

[键盘舞者113]

引用 2 楼 SAKA007 的回复:

真的非常感谢您！我是新手，能多请教您一个问题吗，为什么我之前用的tView.setOnTouchListener(new mOnTouch()) 设置监听事件就不行呢？

因为OnTouchListener拦截不到触摸时间，不懂得网上搜搜 Android事件分发

[SAKA007]

好的！再次谢谢您！