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.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”