performClick 是使用代码主动去调用控件的点击事件（模拟人手去触摸控件）

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boolean android.view..performClick()

Call this view's OnClickListener, if it is defined.

Returns:

True there was an assigned OnClickListener that was called, false otherwise is returned.

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@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_my);

btn1 = (Button) findViewById(R.id.button1);

tv1 = (TextView) findViewById(R.id.textView1);

btn1.performClick();

btn1.setOnClickListener(new OnClickListener() {

@Override

public void onClick(View v) {

tv1.setText("已经被点击过了");

}

});

}

上述方式写，tv1的文字就是默认文字，仅仅有把setOnClickListener的声明写在performClick后面，直接执行程序才干显示“已被点击过了”