4 课后答案【khdaw_lxywyl】(16)

addWindowListener(new WindowAdapter(){ public void windowClosing(WindowEvent we){ System.exit(0); }} ); }

public void actionPerformed(ActionEvent e){ if (e.getSource()==file_new){ txtAr.setText(null); } else if (e.getSource()==file_open){ } else if (e.getSource()==file_save){ } else if (e.getSource()==file_exit){ System.exit(0); //退出 } else if (e.getSource()==edit_copy||e.getSource()==btn_copy){ //复制的实现 strtmp.delete(0,strtmp.length());

strtmp.append(txtAr.getSelectedText()); } else if (e.getSource()==edit_pase||e.getSource()==btn_pase){ //粘贴的实现 txtAr.insert(strtmp.toString(),txtAr.getSelectionEnd()); } else if (e.getSource()==edit_cut||e.getSource()==btn_cut){ //剪切的实现 strtmp.delete(0,strtmp.length());

strtmp.append(txtAr.getSelectedText()); String strtmp1=new String(txtAr.getText().substring(0,txtAr.getSelectionStart())); String strtmp2=new String(txtAr.getText().substring(txtAr.getSelectionEnd(),txtAr.getText().length())); //返回一个新的 String，它包含此序列当前所包含的字符子序列。 txtAr.setText(strtmp1+strtmp2); } else if(e.getSource()==edit_del||e.getSource()==btn_del){ String strtmp1=new String(txtAr.getText().substring(0,txtAr.getSelectionStart())); String strtmp2=new String(txtAr.getText().substring(txtAr.getSelectionEnd(),txtAr.getText().length())); //返回一个新的 String，它包含此序列当前所包含的字符子序列。 txtAr.setText(strtmp1+strtmp2); } }

public static void main(String[] args){

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